Pantech PG-1210, Руководство по обслуживанию

Страница: 15 / 45

PG-1210 Service Manual
to be compatible only with a BBIC from the same supplier in order to address the complex dc offset
issues. However, since the Aero II transceiver has no requirement for BBIC support of complex dc
offset compensation, it is able to interface to all of the industry leading baseband ICs.
The receive (RX) section integrates four differentialinput low noise amplifiers (LNAs) supporting the
GSM 850 (869–894 MHz), E-GSM 900 (925–960 MHz), DCS 1800 (1805–1880 MHz), and PCS 1900
(1930–1990 MHz) bands. The LNA gain is controlled with the LNAG bit.
A quadrature image-reject mixer downconverts the RF signal to a low intermediate frequency (IF).
The mixer output is amplified with an analog programmable gain amplifier (PGA) that is controlled
with the AGAIN bits. The quadrature IF signal is digitized with high resolution analog-to-digital
converters (ADCs).
The ADC output is downconverted to baseband with a digital quadrature local oscillator signal. Digital
decimation and FIR filters perform digital filtering, and remove ADC quantization noise, blockers, and
reference interferers. The response of the FIR filter is programmable to a flat passband setting and a
linear phase setting. After filtering, the digital output is scaled with a PGA, which is controlled with the
DGAIN bits.
The LNAG, AGAIN, and DGAIN register bits should be set to provide a constant amplitude signal to
the baseband receive inputs.
Digital-to-analog converters (DACs) drive differential I and Q analog signals onto the BIP, BIN, BQP,
and BQN pins to interface to standard analog-input baseband ICs.
The receive DACs are updated at 1.083 MHz and have a first-order reconstruction filter with a 1 MHz
bandwidth. No special processing is required in the baseband for dc offset compensation. The receive and
transmit baseband I/Q pins are multiplexed together in a 4-wire interface (BIP, BIN, BQP, and BQN). The
common mode level at the receive I and Q outputs is programmable with the DACCM bits, and the fullscale level
is programmable with the DACFS bits.
4.2.3.2 Receiver Part
ASM (Antenna Switch Module)
ASM consists of Tx filter, having an antenna port, and dual configuration with the transmitting path
isolated from the receiving path. A signal receives from the antenna of frequency band which is
881.5
± 12.5MHz for GSM850 bands, 1842.5 ± 37.5 MHz for DCS bands, and 1960 ± 30 MHz for
PCS bands and transmits it to the saw filter for each band. The Tx filter passes through the output
signals of frequency band that is 836.5MHz
±
12.5MHz for GSM850 bands, 1747.5
±
37.5 MHz for
DCS bnads, and 1880 ± 30 MHz for PCS bands from the power amplifier and transmits it to the
antenna. The maximum insertion loss is about 1.5 dB for the receiving bands at 25
o
C and about 1.5
dB for the transmitting bands at 25
o
C.
SAW Filter (
BPF / Band select filter
)
The F501 filter is for the GSM850 band signals which range 881.5 ± 12.5MHz with low insertion
loss. the F502 filter is for the DCS band signals which range 1842.5
±
37.5 with low inserton loss.
14
PANTECH